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Publication numberUS5243932 A
Publication typeGrant
Application numberUS 07/866,516
Publication dateSep 14, 1993
Filing dateApr 10, 1992
Priority dateApr 12, 1991
Fee statusPaid
Also published asCN1028791C, CN1066909A, DE69202617D1, DE69202617T2, EP0509372A1, EP0509372B1
Publication number07866516, 866516, US 5243932 A, US 5243932A, US-A-5243932, US5243932 A, US5243932A
InventorsRobert Herrmann
Original AssigneeS.E.M.T. Pielstick
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Pilot/main fuel injection method for diesel engines
US 5243932 A
Abstract
A fuel injection method for diesel internal combustion engines uses main injection of a gas main fuel and pilot injection of a liquid secondary fuel to initialize combustion of the main fuel. The liquid fuel is injected by an injector pump designed to enable the engine to achieve its maximum power with the liquid fuel only. The pilot injection comprises a mixture of water and liquid fuel.
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Claims(2)
I claim:
1. Fuel injection method for a diesel internal combustion engine comprising effecting a main injection of a gas main fuel simultaneously with a pilot injection of a liquid secondary fuel to initialize combustion of the main fuel, wherein the liquid fuel is effected via an injector pump designed to enable the engine to achieve its maximum power with the liquid fuel only, wherein the step of pilot injection comprises the injection of a mixture of water and liquid fuel having a volume of liquid fuel contained in the mixture which is the thermodynamically necessary minimum volume compatible with precision of the injector pump and dimensions of the injector atomizer holes and wherein the volume of liquid fuel of the mixture in the pilot injection is in the range of 5 to 10% of the maximum volume that can be injected by the pump.
2. Method according to claim 1 wherein the volume of the liquid fuel in the pilot injection is more preferably in the range 2% to 7% of the maximum volume that can be injected by the pump.
Description
BACKGROUND OF THE INVENTION

1. Field of the invention

The present invention concerns a fuel injection method for diesel internal combustion engines using main injection of a gas main fuel and pilot injection of a liquid secondary fuel which initializes combustion of the main fuel. This is known as dual fuel injection.

2. Description of the prior art

The prior art injection method for dual fuel diesel engines which operate with two fuels, one a gas and the other a liquid, is to initialize the combustion of the main fuel (the gas) by injecting a liquid fuel representing 5 to 10% of the maximum volume that can be injected by the injector pump. The injector pump is designed to enable the engine to achieve its maximum power from the liquid fuel only, in the temporary absence of the gas fuel.

The minimum volume of liquid fuel injected is limited by the geometrical precision with which the injector pump and injector components are manufactured. This precision determines the lower limit below which it is no longer possible to guarantee a balance between the cylinders and the regular injection of a sufficient volume to initialize combustion (approximately equivalent to 2% of the maximum energy input). The minimum volume of liquid fuel injected is further limited by the dimensions of the holes of the injector atomizer which are optimized for correct atomization at full engine power. They are then too large to atomize properly a few percent of the maximum flowrate.

Experience shows that reducing the volume of the pilot injection reduces exhaust carbon monoxide and nitrogen oxides. What is more, the high cost of the liquid fuel is an incentive to reducing its use.

The present invention proposes to reduce the liquid fuel pilot injection volume to the thermodynamically sufficient minimum independently of the precision with which the injector pump is manufactured and independently of the dimensions of the atomizer holes. This can be achieved by mixing water with the liquid fuel.

SUMMARY OF THE INVENTION

The invention consists in a fuel injection method for diesel internal combustion engines using main injection of a gas main fuel and pilot injection of a liquid secondary fuel to initialize combustion of the main fuel, the liquid fuel being injected by an injector pump designed to enable the engine to achieve its maximum power with the liquid fuel only, in which method the pilot injection comprises a mixture of water and liquid fuel.

The invention will be better understood and other advantages will emerge from the following description given by way of non-limiting example.

DETAILED DESCRIPTION OF THE INVENTION

Duel fuel engines usually employ one injector pump for the liquid fuel for each cylinder of the engine, each cylinder having its own injector. Gas is fed into a cylinder through its own distribution system.

In an engine of this type the liquid fuel is injected by an injector pump designed to enable the engine to achieve its maximum power from the liquid fuel only.

Mixing water with the liquid fuel in proportions enabling the pilot injection to initialize combustion solves the problem of the regularity of the volume injected by the pump because the volume of mixture injected by the pump becomes reasonable (between 5 and 10% of the maximum volume that can be injected by the pump, for example). Much better atomization in the injector is also achieved.

An advantage of the invention is that no modification is required to the engine, the fuel-water mixture being prepared outside the engine by a known method.

The volume of liquid fuel contained in the mixture can be reduced to the thermodynamically necessary minimum volume compatible with the precision of the injector pump and the dimensions of the injector atomizer holes. This minimum volume is easily determined by experiment.

A volume of liquid fuel in the mixture representing 2% to 7% of the maximum volume that can be injected by the pump is entirely satisfactory for correct operation of the engine.

The volume of the pilot injection, that is to say the quantity of mixture injected, may then represent between 5 and 10% of the maximum volume that can be injected by the pump.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US4403944 *Oct 10, 1979Sep 13, 1983Pyykkoenen PenttiAuxiliary device for oil burner for mixing water and oil for combustion
US4597671 *Apr 30, 1984Jul 1, 1986Ernesto MarelliApparatus for emulsifying and atomizing fluid fuels with secondary fluids, in particular water
US4619240 *Oct 31, 1983Oct 28, 1986Anker Gram & Associates Ltd.Fuel oil injection engine
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US4732114 *Jul 3, 1986Mar 22, 1988Daimler-Benz AktiengesellschaftProcess for producing a diesel-fuel/water emulsion for a diesel engine
US4831993 *Dec 28, 1987May 23, 1989Erik KelgardMethod of operating carburetted dual-fuel engines with diesel pilot oil injection
US4834055 *Feb 26, 1988May 30, 1989Sulzer Brothers LimitedFuel injection system
US4924822 *Jun 1, 1988May 15, 1990Mitsubishi Jukogyo Kabushiki KaishaGas feed system for a gas-fired diesel engine
US4955326 *Apr 12, 1989Sep 11, 1990Cooper Industries, Inc.Low emission dual fuel engine and method of operating same
US5024195 *Jun 7, 1990Jun 18, 1991Pien Pao CMulti-fuel compression-ignition engine and fuel injection pump therefor
US5136986 *Apr 26, 1991Aug 11, 1992Energy Conversions, Inc.Dual fuel injection structure
US5140959 *Jan 28, 1991Aug 25, 1992Durbin Enoch JMethod and apparatus for operation of a dual fuel compression ignition combustion engine
EP0027682A1 *Jul 18, 1980Apr 29, 1981Caterpillar Tractor Co.Fuel injection apparatus
EP0237071A1 *Mar 12, 1987Sep 16, 1987Societe D'etudes De Machines Thermiques S.E.M.T.Fuel injection device for internal-combustion engines for the injection of two fuels
FR2383315A1 * Title not available
JPS6299667A * Title not available
Non-Patent Citations
Reference
1 *Patent Abstracts of Japan, vol. 11, No. 316 (M 631) (2763) Oct. 15, 1987, & JP A 62 99667 (Mazda) May 9, 1987.
2Patent Abstracts of Japan, vol. 11, No. 316 (M-631) (2763) Oct. 15, 1987, & JP-A-62 99667 (Mazda) May 9, 1987.
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US5529024 *Oct 26, 1994Jun 25, 1996Daimler-Benz A.G.Fuel injection system for an internal-combustion engine
US5682842 *Dec 6, 1996Nov 4, 1997Caterpillar Inc.Fuel control system for an internal combustion engine using an aqueous fuel emulsion
US5765537 *Jan 17, 1997Jun 16, 1998Caterpillar Inc.Fuel recirculation system
US6032617 *May 27, 1998Mar 7, 2000Caterpillar Inc.Dual fuel engine which ignites a homogeneous mixture of gaseous fuel, air, and pilot fuel
US6095101 *Jan 26, 1998Aug 1, 2000Man B&W Diesel A/SInternal combustion engine of the diesel type for combustion of gas, and a method of supplying such an engine with fuel
US6230683Dec 8, 1999May 15, 2001Cummins Engine Company, Inc.Premixed charge compression ignition engine with optimal combustion control
US6276334Feb 23, 1999Aug 21, 2001Cummins Engine Company, Inc.Premixed charge compression ignition engine with optimal combustion control
US6286482Aug 22, 1997Sep 11, 2001Cummins Engine Company, Inc.Premixed charge compression ignition engine with optimal combustion control
US6378487Sep 1, 2000Apr 30, 2002International Truck And Engine CorporationMethod and apparatus for pre-pilot fuel injection in diesel internal combustion engines
US6386149May 11, 1999May 14, 2002Clean Fuel Technology, Inc.Method of operating an engine with a mixture of gaseous fuel and emulsified pilot fuel to reduce nitrogen oxide emissions
US6863034Jan 17, 2003Mar 8, 2005Robert D. KernMethod of controlling a bi-fuel generator set
US6915776Oct 15, 2003Jul 12, 2005Cummins Inc.Premixed charge compression ignition engine with optimal combustion control
EP0967372A2 *May 21, 1999Dec 29, 1999Caterpillar Inc.Dual fuel engine which ignites a homogeneous mixture of gaseous fuel, air, and pilot fuel
WO2004091758A1 *Apr 16, 2004Oct 28, 2004David John LongmanAn improved fuel reformer and mixing chamber therefor
Classifications
U.S. Classification123/25.00E, 123/304, 123/526, 123/575, 123/27.0GE
International ClassificationF02B7/02, F02M43/00, F02B3/06, F02D19/08, F02D41/38, F02B47/02, F02M45/04, F02B47/00, F02M25/022
Cooperative ClassificationF02B47/02, F02B7/02, F02B2201/064, F02B3/06, F02M25/0228
European ClassificationF02M25/022E, F02B7/02, F02B47/02
Legal Events
DateCodeEventDescription
Feb 17, 2005FPAYFee payment
Year of fee payment: 12
Mar 13, 2001FPAYFee payment
Year of fee payment: 8
Mar 13, 1997FPAYFee payment
Year of fee payment: 4
Jun 4, 1992ASAssignment
Owner name: S.E.M.T. PIELSTICK, FRANCE
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:HERRMANN, ROBERT;REEL/FRAME:006143/0191
Effective date: 19920406